1. Field of the Invention
The present invention relates to a thin film transistor (“TFT”) substrate and a method for fabricating the same, and more particularly, to a TFT substrate and a method for fabricating the same in which an organic semiconductor layer is provided.
2. Description of the Related Art
A TFT substrate includes a TFT as a switching and driving device for controlling and driving an operation of each pixel, such as within a display panel of a display device. Each TFT includes a gate electrode, source and drain electrodes which are separated by the gate electrode so as to define a channel region, and a semiconductor layer. The semiconductor layer is formed of amorphous silicon (“a-Si”) or polysilicon. However, an organic semiconductor has been recently substituted for the semiconductor layer.
Since the organic semiconductor can be formed at room temperature and atmospheric pressure, there is an advantage that it can reduce a fabricating cost and also be applied to a plastic substrate which is weak to heat. However, the organic semiconductor is disadvantageous in that it is weak in chemical resistance and plasma resistance.
In the organic TFT provided with the organic semiconductor as described above, an organic semiconductor material is applied to the channel region between the source and drain electrodes, and then patterned by a photolithographic process so as to form an organic semiconductor layer, whereby the organic TFT is fabricated.
However, this fabricating method is very complicated due to a large number of processes, and a characteristic of the organic semiconductor layer may be deteriorated by a chemical material, etc., which is used in forming source and drain electrodes, a data wire, a gate wire and so forth. Therefore, it is difficult to ensure stability and reliability in a characteristic of the organic TFT. Particularly, when the organic semiconductor material is applied and then patterned by the photolithographic process, as described in the conventional method, since the characteristic of the organic semiconductor layer is deteriorated, the characteristic of the organic TFT may be damaged.